An example for the use of an interventional device is cardiac ablation which is a procedure for curing cardiac arrhythmia. Preferably, the process of the cardiac ablation is monitored in situ. An ablation catheter with multiple ultrasound transducers in its tip enables the physician in the electro-physiology lab to assess in real time certain relevant parameters of the heart wall from the inside.
An example of an ultrasound transducer system for cardiac ablation monitoring in discussed in WO 2012/066430 A1.
However, unless a casing transparent to the monitored signal (e.g. ultrasound) is employed, i.e. if there are openings in the casing of the interventional device through which signals are emitted or received, complications during the treatment procedure may be caused by discontinuities in the surface of the interventional device.
In particular, if there is a mechanical discontinuity on the ablation catheter tip, there is a potential of thrombi formation, which can cause thromboembolic events with severe consequences (e.g. a stroke).
Openings which are provided in the case for irrigation purposes, for example, usually do not pose such threat as there is a (continuous) flow of saline irrigation fluid during the procedure. In contrast, in the case of an opening of the casing which might even include a distinct step between a surface of the transducer arrangement and the outer surface of the casing, such step is a potential site for thrombi formation due to the lack of a forced flow in such regions during treatment procedure.